1. Field of Invention
This invention relates to a facsimile communication apparatus for allowing a plurality of facsimile machines designed for general telephone networks to communicate with each other via a data communication network, such as a local area network (LAN), and to a program recording unit which stores a program used in the facsimile communication apparatus. This invention also relates to a facsimile communication apparatus for allowing a plurality of facsimile machines to communicate with each other in real time via an Internet Protocol network (referred to as an IP network) based on the IETF (Internet Engineering Task Force), and to a program recording unit storing a program for controlling the facsimile communication apparatus.
2. Description of the Related Art
FIG. 1 illustrates a conventional facsimile communication system using a data communication network, such as an LAN. The transmission side facsimile machine 1 is a G-3 facsimile machine designed for general telephone networks, which is categorized according to the T.30 Recommendation standardized by the ITU-T (International Telecommunications Union, Telecommunication Standardization Department). The facsimile machine 1 is connected to the facsimile communication apparatus 10A via a telephone network 2. The facsimile communication apparatus (i.e., the gateway) 10A converts the communication protocol between the telephone network 2 and the LAN 4. The LAN 4 is further connected to another facsimile communication apparatus (i.e., gateway) 10B, to which the receiving side facsimile machine 7 is connected via a telephone network 6. The facsimile machines 1 and 7 have the same standard, and they can mutually transmit and receive image information via the telephone networks. The facsimile communication apparatus 10B has the same structure as the facsimile communication apparatus 10A, and the explanation on it will be omitted.
As shown in FIG. 2, the facsimile communication apparatus 10A has a terminal accommodation circuit 3a, to which a plurality of facsimile machines 1a through 1n are connected via the corresponding telephone lines 2a, 2b, . . . , 2n of the telephone network 2. The terminal accommodation circuit 3a is connected to a switch circuit 3b which selects the line which is currently requesting a facsimile transmission from among the telephone lines 2a through 2n. A CODEC 3c is connected to the switch circuit 3b in order to terminate the selected line. The CODEC 3c is a encoder/decoder which converts analog signals received from the telephone line 2a into digital signals, and which decodes digital signals into analog signals in order to output data to the telephone line 2a. 
The terminal accommodation circuit 3a, the switch circuit 3b and the CODEC 3c are connected to the CPU 3e via a common bus 3d. The CPU 3e controls the overall operations of the facsimile communication apparatus 10A. A memory 3f and a LAN control circuit 3g are also connected to the common bus 3d. The memory 3f temporarily stores digitized information prior to transmitting the digitized information. The LAN control circuit 3g performs data transfer in a packet format to and from another facsimile communication apparatus 10B via the LAN 4.
The facsimile machine 1 of FIG. 1 is connected to the facsimile machine 7 via the telephone line 2, the facsimile communication apparatus 10A, the LAN 4, the facsimile communication apparatus 10B, and the telephone line 6, in that order. If pixel information is transmitted from the facsimile machine 1a of FIG. 2 to the facsimile machine 7, the pixel data read by the facsimile machine 1a from the original document is encoded according to a prescribed coding rule. The encoded pixel data is modulated by, for example, a 9600 bps MODEM installed in the facsimile machine 1a to produce an analog signal in the voice frequency band. The analog signal is transmitted to the facsimile communication apparatus 10A through the telephone line 2a. The CODEC 3c of the facsimile communication apparatus 10A samples the analog signal supplied via the telephone line 2a based on a sampling signal of, for example, 8 KHz, and converts the sampled analog signal into an 8-bit digital signal for each sampling.
Thus, the analog signal is converted into a 64 Kbps digital signal by the CODEC 3c, which is then read by the CPU 3e via the common bus 3d. The CPU 3e edits the digital signal into a packet data of a predetermined size, and temporarily stores the packet data in the memory 3f. The packet data stored in the memory 3f is read out by the LAN control circuit 3g, and transmitted to the receiving side facsimile communication apparatus 10B via the LAN 4. In the facsimile communication apparatus 10B, the packet data received from the LAN control circuit 3g is temporarily stored in a memory. Then, the stored data is read out by a CPU corresponding to the CPU 3e, and supplied to a CODEC corresponding to the CODEC 3c, which converts the data into an analog signal and outputs the analog signal to the facsimile machine 7 via the telephone network 6. Thus, the analog signal transmitted from the facsimile machine 1a is converted into a digital signal by the CODEC 3c of the facsimile communication apparatus 10A, and transferred as a packet data to the receiving side facsimile communication apparatus 10B via the LAN 4.
However, the conventional facsimile communication system has several problems.
Because the transfer path of the LAN 4 is divided into a plurality of channels in order to transfer the data in a packet format, the transfer delay time of the packet data is not constant. In addition, if the traffic of the LAN 4 is heavy, the packet data may be lost half way through the transmission path. For these reasons, the analog signals which are being decoded by the CODEC 3c of the receiving side facsimile communication apparatus 10B may sometimes be interrupted and, as a result, wrong data is received by the receiving side facsimile machine 7.
Furthermore, although the inherent data transfer rate between the facsimiles machines 1a and 7 is, for example, 9600 bps, the data is transferred at 64 Kbps in the LAN 4, which is inefficient from the standpoint of data transfer capacity.
Therefore, the object of the invention is to overcome the problems in the prior art, and to provide a facsimile communication system that can perform facsimile communication in an efficient manner from the standpoint of data transfer capacity with little transfer errors.
In order to achieve the object, in the first aspect of the invention, a facsimile communication apparatus comprises: facsimile procedure controller that receives and transmits control information and pixel information from and to facsimile machines connected to the facsimile communication apparatus according to a predetermined procedure; a first information converter that converts the control information and the pixel information received from the facsimile machines into a control packet signal and a pixel packet signal of predetermined formats; data transmitter/receiver that transmits the control packet signal and the pixel packet signal produced by the first information converter via a data communication network, and that receives a control packet signal and a pixel packet signal transmitted via the data communication network; and a second information converter that converts the control packet signal and the pixel packet signal received by the data transmitter/receiver into control information and pixel information which are to be output to a receiving side facsimile machine. The facsimile communication apparatus may further comprise a memory which stores a predetermined amount of pixel packet signals received by the data transmitter/receiver and which outputs the stored signals to the second information converter when the predetermined amount of signals are accumulated.
In the second aspect of the invention, a facsimile communication apparatus comprises: means for calling the receiving side facsimile machine based on a request for connection to the receiving side facsimile machine as received from the data communication network; means for temporarily storing the image data transmitted from the transmission side facsimile machine via the data communication network in a memory; means for starting transmission of the image data to the receiving side facsimile machine when a data-receiving control signal representing the acceptability of image data is received from the receiving side facsimile machine, provided that a desirable amount of image data is stored in the memory at the time of receipt of the data-receiving control signal; and waiting controller for transmitting a prescribed wait control signal to the receiving side facsimile machine in order to have the receiving side facsimile machine stand by if the desirable amount of image data has not been stored in the memory at the time of receipt of the receiving control signal representing the acceptability of the image data from the receiving side facsimile machine.
In still another aspect of the invention, a program recording unit for storing a program for controlling a facsimile communication apparatus is provided. This program recording unit comprises: means for causing the facsimile communication apparatus to call the receiving side facsimile machine based on a request for connection to the receiving side facsimile machine received from the data communication network; means for causing the facsimile communication apparatus to temporarily store the image data transmitted from the transmission side facsimile machine via the data communication network in the memory; means for causing the facsimile communication apparatus to start transmitting the image data to the receiving side facsimile machine when the facsimile communication apparatus receives a data-receiving control signal that represents the acceptability of image data of the receiving side facsimile machine, provided that a desirable amount of image data is stored in the memory at the time of receipt of the data-receiving control signal; and waiting controller for causing the facsimile communication apparatus to transmit a prescribed wait control signal to the receiving side facsimile machine in order to have the receiving side facsimile machine stand by if the desirable amount of image data has not been stored in the memory at the time of receipt of the receiving control signal representing the acceptability of the image data from the receiving side facsimile machine.
The waiting controller comprise determination means for determining whether or not the receiving side facsimile machine can stand by, while maintaining a data reception mode, if the desirable amount of image data has not been accumulated in the memory at the time of receipt of the data-receiving control signal. If it is determined that the receiving side facsimile machine can wait in the data reception mode, then waiting means causes the facsimile communication apparatus to wait for further storage of image data until the desirable amount of image data is stored in the memory. On the other hand, if it is determined that the receiving side facsimile machine is not able to wait in the data reception mode, wait control signal transmitter causes the facsimile communication apparatus to transmit the wait control signal to the receiving side facsimile machine.
The desirable amount of image data stored in the memory can be calculated by multiplying the transmission rate of the image data determined by negotiation between the transmission side facsimile machine and the receiving side facsimile machine by a predetermined time stored in advance. Alternatively, the desirable amount of image data can also be calculated by multiplying the communication rate determined by negotiation between the transmission side facsimile machine and the receiving side facsimile machine by a predetermined time stored in advance. The transmission side facsimile machine and the receiving side facsimile machine are G3 facsimile machines categorized based on the T.30 Recommendation. In this case, the data-receiving control signal is a data-receivable state confirmation signal CFR according to the T.30 Recommendation, and the wait control signal is a transmission site identification signal TSI according to the T.30 Recommendation.
The contents of patent application H9-131812 filed in Japan on May 22, 1997 and a patent application filed in Japan on Apr. 22, 1998, the application number is not yet assigned, are incorporated hereinto by reference.